Whenever I'm trying to close a file that has been changed, I get the save file dialog

I remember that the Don't Save button used to have focus, so I could press it using Spacebar, while pressing Enter would click on Save. But now on Lion, I'm unable to find a way to press the Don't Save using keyboard only, since Tab doesn't change focus to anything, and space doesn't work either.

This is the same for all file save dialogs in the system.Is there any way I can press the Don't Save button using keyboard only?

Note: Unlike in Windows, you need to hit space to trigger a highlighted box that is not the default one! (If this is not natural to you, here's something that helps many to remember tab and space rather than just enter. The space bar is the keyboard version of a one button mouse with the tab moving the mouse's pointer for you.)